1. Field of the Invention
The present invention relates generally to angle sensors and, more particularly, to an angle sensor, configured to compensate eccentricity of a main gear rotated by a rotating shaft, thus inhibiting abrasion of a gear and reduction in tooth strength and thereby improving operational reliability and durability.
2. Description of the Related Art
Generally, an auxiliary steering system supported by additional power is used as a device for ensuring steering stability of a vehicle. Conventionally, the auxiliary steering system uses a hydraulic pressure. However, an electronic power steering system, which consumes less power and is excellent in accuracy, has been recently used.
Such an electronic power steering system (EPS) drives a motor by an electronic control unit depending on driving conditions detected by a vehicle speed sensor, an angle sensor and a torque sensor, thus ensuring turning stability and providing a rapid restoring force, and thereby allowing a driver to safely drive a vehicle.
The angle sensor is a device that outputs an electric signal in proportion to a rotation angle of a steering shaft. Recently, the angle sensor is frequently combined with the torque sensor measuring steering torque to form an assembly.
FIG. 1 is a plan view illustrating an example of the angle sensor.
In the case of the angle sensor, as a driver rotates a steering wheel, a main gear 20 attached to a steering shaft rotates in conjunction with the steering wheel, and there occurs a difference in rotation angle between input and output shafts of the steering shaft. At this time, a magnetic device detects magnetic fields and rotating directions of magnets 31 and 32 attached to subsidiary gears 21 and 22 engaging with the main gear 20, and thereafter sends a detected signal to an electronic control unit.
The main gear 20 and the subsidiary gears 21 and 22 are coupled to an interior of a housing 10. The main gear 20 is integrally formed with a coupling member by injection molding, or is coupled to the coupling member by bonding. Here, the coupling member is provided on a portion of the housing 10 through which a rotating shaft passes.
However, such a coupling structure is problematic in that, when vibration is transmitted to the housing or the coupling member, it leads to vibration of the main gear. Further, when eccentricity occurs with respect to the rotating shaft, gears may be worn out and strength may be lowered. Consequently, the vibration and eccentricity may cause the malfunction or damage of the entire angle sensor.